Imidazolinone Herbicides
These herbicides inhibit acetolactase synthase (same mode of action as sulfonyluyrea herbicides) which is responsible for the production of the amino acids isoleucine, leucine and valine. Without these amino acids, certain proteins can not be produced and plants are doomed. Examples of imidazolinone herbicides are: imazamox, imazapic, imazapyr, imazaquin and imazethapyr. In general, these herbicides are more active on broadleaf than grasses. These herbicides are taken up by both roots and shoots and persistance can be troublesome. Resistance is both problematic and increasing.
Symptoms on plants affected by these herbicides include cessation of growth, leaf distortion, yellowing of shoot tips, yellowing between veins on leaves, purple coloration of foliage of dicot plants and death/browning of foliage. Roots of affected plants can have a "bottlebrush" appearance - numerous short lateral roots.
Photographs by Dr. Michael Pfeiffer
Imazapyr - Eucalyptus sp.
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Imazapyr - Chamaerops humilis
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imazapyr - Nerium oleander
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imazapyr - Nerium oleander
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imazapyr - Rosa sp
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Imazapyr - Rosa sp.
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